Chosen Solution

This version works for me on a desktop Linux Firefox 17 version.
I do not have a mobile device to test it, but I assume it will work there as well.

I've modified the about:synckey extension to make it work in Firefox 17.
*http://www.freefilehosting.net/aboutsynckey-11-fnfx
This version works for me on a desktop Linux Firefox 17 version.<br />
I do not have a mobile device to test it, but I assume it will work there as well.